Paratroopers.
It is old school but it is a good use of resources for this mission and I suspect will be the minimum to achieve this end. It is analogous to Operation Shock carried out in 1968 by Israeli paratroopers against elements of Egyptian electrical infrastructure. A modern mass attack as is proposed will not have much need of individual infantrymen but the dispersed, remote and individually vulnerable elements of the windmill farm are perfect for this sort of attack. One can use an ordinary plane for the drop which frees up specialized aircraft for uses elsewhere.
Paratroopers will be dropped some kilometers from their target in advance of the mass attack. They will make their way across the countryside on foot, fanning out across the windmill installation. A windmill is a great target for a paratrooper as a single rifle shot can irrevocably disable a windmill.
After all windmills have been shot, paratroopers make their way to an extraction point / points, possibly by car or train.
In addition to being effective and efficient, the first person viewpoint of the paratrooopers is dramatic and lends itself to a work of fiction. The recounting of the paratrooper experience in linked Operation Shock is a fine example.
I must add that this would be called Operation Quixote. The South Dakotan officer pronounces it "Quicks-Oat".